In the semiconductor manufacturing process, after a wafer has been processed in the usual way with growth of epitaxial layers, diffusions of dopants and other species, and formation of insulating layers, followed by metallizations that are patterned to form the desired connections to each of the active devices formed in the wafer, individual chips of one or more active devices have to be separated from the wafer or bar. One standard technique for doing this is to scribe the wafer surface with a diamond scribe and then fracture the wafer along the scribe lines by applying pressure from the back side of the wafer. Another common technique is to use a chip chopping apparatus. Both of these techniques depend upon mechanically removing material from the semiconductor crystal, which requires that the removing tool must penetrate the layers on the wafer surface before reaching the underlying crystal. There are several problems that may arise as a result. Scribing is time-consuming. Moreover, when the surface of the device is scratched, the integrity of the metallization may be compromised, which can lead to difficulties. Another problem is that scratches may cause in the semiconductor crystal dislocations which may propagate to active device regions with undesirable consequences.
Further, for certain kinds of devices, such as II-V or II-VI laser devices made in chips separated from semiconductor bars, chip chopping does not work well, leaving only the scribing process with its attendant problems. Moreover, with the laser chips, the chip device is frequently mounted upside down on a heat sink. Any metallization defects produced by the scribing process can cause operational problems of the laser device.